diff -r 48c4eec2b7e6 -r 8c2e4d02f4ef wp/wp-includes/rest-api/endpoints/class-wp-rest-template-autosaves-controller.php
--- a/wp/wp-includes/rest-api/endpoints/class-wp-rest-template-autosaves-controller.php	Fri Sep 05 18:40:08 2025 +0200
+++ b/wp/wp-includes/rest-api/endpoints/class-wp-rest-template-autosaves-controller.php	Fri Sep 05 18:52:52 2025 +0200
@@ -175,6 +175,11 @@
 		$template = _build_block_template_result_from_post( $item );
 		$response = $this->parent_controller->prepare_item_for_response( $template, $request );
 
+		// Don't prepare the response body for HEAD requests.
+		if ( $request->is_method( 'HEAD' ) ) {
+			return $response;
+		}
+
 		$fields = $this->get_fields_for_response( $request );
 		$data   = $response->get_data();